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Home » Guide » Arthropods (Arthropoda) » Hexapods (Hexapoda) » Insects (Insecta) » Flies (Diptera) » Orthorrhapha » Asiloidea » Robber Flies (Asilidae) » Asilinae » Hammertails (Efferia) » Nerax group (Efferia Nerax group)
Photo#207291
Robber Fly - Efferia
Copyright © 2008 David P. McNicholas

Robber Fly - Efferia
New Vernon, Morris County, New Jersey, USA
July 28, 2008
Size: 1 inch
Robber Fly feeding on a small fly. Probably from Promachus. Maybe Promachus fitchi?
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Contributed by David P. McNicholas on 28 July, 2008 - 8:26pm
Last updated 16 July, 2015 - 7:47am

Moved
Moved from Efferia.
… Herschel Raney, 23 October, 2008 - 3:59pm login or register to post comments

guessing
I'm just getting into these guys, but it looks more like Efferia aestuans to me.
… Jason Forbes, 28 July, 2008 - 8:47pm login or register to post comments

 
Robber fly
The orange tibia are consistent with Efferia but the abdomen seemed to look more like the pictures that i have of Promachus and the Emerald eye seemed to confirm.
What are the defining features?
… David P. McNicholas, 29 July, 2008 - 8:38am login or register to post comments

 
Those
swordlike ovipositors are only in the Efferia group. Eye color is not reliable. And Promachus have elongate abdomens in the female but they have the distinctive step shape made from several segments.

And Promachus fitchii is an endangered beast in the NE now.
… Herschel Raney, 29 July, 2008 - 10:27am login or register to post comments

 
Robber fly
Thank you for the help.
some of my references are old and maybe out-of-date.
… David P. McNicholas, 29 July, 2008 - 7:48pm login or register to post comments

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